The present invention relates to a liquid purification apparatus for purifying a wastewater, i.e., a liquid to be treated containing at least one of minute particles (for example, minute particles of dioxins, bacteria and the like), metal Ions, heavy metal ions and the like, such as, for example, a wastewater from an incinerator.
Conventionally, filtration of a wastewater containing very fine minute particles such as those of 0.1 xcexcm or the like could not be effected even with ceramic filters having many minute apertures, and no other measure has been known except removal with hollow yarns. In addition, running costs required for an operation for solving clogging of ceramic filters are considerably high.
Therefore, in the conventional cases, minute particles were aggregated and precipitated by adding an aluminum or magnesium aggregation agent to the waste fluid, and the precipitated aggregates were removed by filtering with a press filter.
In addition, no other measure has been known for removal of heavy metals in discharged water except removal with a chelating agent effected separately from the above operation or removal with an ion-exchange resin.
Measures as described above have been applied in the conventional apparatuses and methods, and removal of very fine minute particles has been made by aggregation and precipitation of the minute particles together with an aggregation agent through addition of the aggregation agent. Therefore, the aggregation agent should be added in a large amount and costs for the aggregation-precipitation product itself as well as its waste treatment could not be ignored. In addition, a large amount of precipitates were produced by the addition of a large amount of the aggregation agent, and hence the operation for filtration thereof under pressure with a press filter became enormous and costs therefore were remarkable.
Moreover, the removal of metal ions and heavy metal ions could only be performed with a chelate agent or an ion-exchange resin; this required an enormous expenses for the initial costs and the running costs and a problem occurred in the regeneration of a chelate agent that a large amount of a concentrated wastewater containing heavy metal ions was produced.
The invention has been made for solving the problems in conventional measures as described above.
The invention is made such that the purification is attained by placing an adsorbent comprising at least basic magnesium sulfate and magnesium hydroxide between a first and a second filter layers, passing a liquid to be treated through the adsorbent, thereby, causing aggregation of minute particles in the liquid to be treated so that a large mass is formed and then trapping it by the second filter layer.
This allows removal of the minute particles in the liquid to be purified without using a large amount of an aggregation agent, and the minute particles to be removed could be trapped and removed with a filter having openings about 100 times as large as the size of the minute particles to be removed.
In the invention, xe2x80x9cpurificationxe2x80x9d does not refer to a simple filtration with a filter, such as a trapping, in a space, of a particulate substance contained in a liquid to be treated by passing the liquid through the space having a given size, but refers to a trapping of a targeted substance in the above described space having a given size after aggregating the substance to form a mass having a certain dimension.
In another feature of the invention, a purification apparatus for a liquid to be treated is provided, such that metal ions are trapped by placing an adsorbent comprising at least basic magnesium sulfate and magnesium hydroxide between a first and a second filter layers, passing the liquid to be treated containing the metal ions through the adsorbent, thereby causing binding of the metal ions, particularly heavy metal ions, in the liquid to be treated to a hydroxyl group in an adsorbent resulting in flocculation, causing aggregation of flocculated particles so that a large mass is formed, and then trapping it by the second filter layer.
This allows removal of the metal ions or the heavy metal ions In the liquid to be treated without using a chelate agent or an aggregation agent.
Another feature of the invention is such that metal ions is trapped by placing an adsorbent comprising at least basic magnesium sulfate and magnesium hydroxide between a first and a second filter layers, electrically charging a direct current by electrode equipments, causing generation of OH ions in the liquid to be treated, causing binding of the OH ions and a hydroxyl group in the above described adsorbent to the metal or heavy metal ions in the liquid to be treated resulting in flocculation, causing aggregation of flocculated particles so that a large mass is formed, and then trapping it by the second filter layer. This allows removal of the metal ions or the heavy metal ions in the liquid to be treated with a low-cost apparatus without using a chelate agent or an aggregation agent.
Another feature of the invention is designed such that metal ions are trapped by placing an adsorbent comprising a powdery cellulose between a first and a second filter layers, electrically charging a direct current by electrode equipments, causing generation of OH ions in the liquid to be treated, causing binding of this OH ions and a hydroxyl group in the above described adsorbent to the metal or heavy metal ions in the liquid to be treated resulting in flocculation, and then trapping flocculated particles by the adsorbent and the second filter layer.
This allows removal of the metal ions or the heavy metal ions in the liquid to be treated with a low-cost apparatus without using a chelate agent or an aggregation agent.